| From | Andi Kleen <> | Subject | [PATCH] [108/139] cs5535-gpio: don't apply errata #36 to edge detect GPIOs | Date | Tue, 1 Feb 2011 16:45:06 -0800 (PST) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Andres Salomon <dilinger@queued.net>
commit 001851659354cce436b749a793f3512a53394d80 upstream.
The edge detect status GPIOs function differently from the other atomic model CS5536 GPIO registers; writing 1 to the high bits clears the GPIO, but writing 1 to the lower bits also clears the bit.
This means that read-modify-write doesn't actually work for it, so don't apply the errata here. If a negative edge status gets lost after resume.. well, we tried our best!
Tested-by: Daniel Drake <dsd@laptop.org> Signed-off-by: Andres Salomon <dilinger@queued.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Andi Kleen <ak@linux.intel.com>
--- drivers/gpio/cs5535-gpio.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
Index: linux-2.6.35.y/drivers/gpio/cs5535-gpio.c =================================================================== --- linux-2.6.35.y.orig/drivers/gpio/cs5535-gpio.c +++ linux-2.6.35.y/drivers/gpio/cs5535-gpio.c @@ -56,15 +56,22 @@ static struct cs5535_gpio_chip { * registers, see include/linux/cs5535.h. */ -static void errata_outl(u32 val, unsigned long addr) +static void errata_outl(struct cs5535_gpio_chip *chip, u32 val, + unsigned int reg) { + unsigned long addr = chip->base + 0x80 + reg; + /* * According to the CS5536 errata (#36), after suspend * a write to the high bank GPIO register will clear all * non-selected bits; the recommended workaround is a * read-modify-write operation. + * + * Don't apply this errata to the edge status GPIOs, as writing + * to their lower bits will clear them. */ - val |= inl(addr); + if (reg != GPIO_POSITIVE_EDGE_STS && reg != GPIO_NEGATIVE_EDGE_STS) + val |= inl(addr); outl(val, addr); } @@ -76,7 +83,7 @@ static void __cs5535_gpio_set(struct cs5 outl(1 << offset, chip->base + reg); else /* high bank register */ - errata_outl(1 << (offset - 16), chip->base + 0x80 + reg); + errata_outl(chip, 1 << (offset - 16), reg); } void cs5535_gpio_set(unsigned offset, unsigned int reg) @@ -98,7 +105,7 @@ static void __cs5535_gpio_clear(struct c outl(1 << (offset + 16), chip->base + reg); else /* high bank register */ - errata_outl(1 << offset, chip->base + 0x80 + reg); + errata_outl(chip, 1 << offset, reg); } void cs5535_gpio_clear(unsigned offset, unsigned int reg)
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